Slide 1
Transcription makes an RNA copy from genetic instructions
Transcription uses the cell’s genetic sequence as a template to build ribonucleic acid, or RNA. It is a first step in expressing many genes.
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The abbreviation RNA names this molecule. It differs chemically from deoxyribonucleic acid (DNA) and usually functions as a single-stranded molecule. Some RNAs carry protein-building information, while others help regulate reactions or form parts of cellular machinery.
Slide 2
Starting-region signals help regulate copying
RNA polymerase, the copying enzyme, begins transcription with help from sequences and proteins that identify a starting region. Gene use can be controlled at this stage.
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A promoter is one such DNA region associated with initiation. Regulatory proteins can encourage or hinder the process, making transcription responsive to signals without changing the underlying DNA sequence.
Slide 3
The growing RNA matches the DNA template
The growing RNA pairs complementary bases with the DNA template. RNA uses uracil where DNA ordinarily uses thymine.
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Only one DNA strand serves as the template for a given transcript. Different genes can use different strands, so a chromosome cannot be described as having one universally read side for every gene.
Slide 4
Many protein-coding copies are processed before use
In eukaryotic cells, which have nuclei, many protein-coding RNA copies are processed before use. Portions can be removed and the remaining segments joined.
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Alternative splicing can produce different mature RNAs from one gene. The result expands possible products, although not every splice form necessarily yields a stable or functional protein.
Slide 5
RNA amount depends on production and breakdown
Cells regulate both production and breakdown of RNA. The amount present reflects these opposing rates as well as current transcription.
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A high RNA measurement does not automatically mean a proportionally high protein amount. Translation efficiency and protein degradation add further controls after the message has been made.
Sources
- Transcription
National Human Genome Research Institute
- Gene Expression
National Human Genome Research Institute
- Deoxyribonucleic Acid DNA
National Human Genome Research Institute